Why Cap didn't support Sokovia Accords ???

Sokovia Accords is well known topic in marvel cinematic universe. It's mainly in Captain America civil war . For Sokovia Accords different avengers have different opinions and thought so they broke . Captain America goes against it while Ironman support it and other avengers either go Cap or Ironman support . First let's talk about Sokovia Accords.

Sokovia Accords was approved by 117 different countries and it will be under United Nations and it is mentioned that Avengers can no longer operates on themselves but got controlled by UN.
Since ,this actually leads to different scenarios. Let's say someone is attacking or robbing in some famous multistore building and there is one avengers who can stop it. If Sokovia Accords signed successfully ,then that Avengers can't stop that events directly. First , someone or the members of Avengers himself report to that incident to government ,then it will be addressed in United Nations ,then meeting will be held and decision will be made for any action to do then only Members of Avengers cab stop that if they said him to do so. Bit what if they said not to stop ,then he will see robbing in front of him. So captain America didn't support it. It could be Even worse if decision are mde late but that accident already happened. It's some sort of binding their will against their own power.